JPH07270084A - Double tube type heat exchanger - Google Patents

Abstract

PURPOSE:To improve corrosion resistance of one end of an inner tube opposed to an inlet water tube. CONSTITUTION:A cover plate material is externally engaged with one end of an inner tube 1 opposed to an inlet water tube 12, and formed in a double structure. The plate material is formed by extending an inner peripheral side cylindrical part 7a of a blocking plate 6a to an opposed part. Or, a cylindrical plate material is separately externally engaged. The plate material is made of aluminum alloy similarly to the respective forming members. A thickness of this part is increased by the plate material. Further, cooling water is not brought into direct contact with the tube 1. Accordingly, a through hole is scarcely formed at the part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The double-tube heat exchanger according to the present invention is incorporated in a vapor compression refrigerator constituting an air conditioner for automobiles to completely evaporate the refrigerant returned to the compressor, or Is incorporated in various cooling devices and used to cool liquids such as water.

[0002]

2. Description of the Related Art A vapor compression refrigerator is incorporated in an automobile air conditioner for cooling and dehumidifying the interior of an automobile. In the case of the vapor compression refrigerator, heat is exchanged between the air for air conditioning and the refrigerant in the evaporator portion arranged in the duct for the air conditioner. With the heat exchange, the refrigerant is evaporated in the evaporator and then returned to the compressor.

Incidentally, when so-called liquid back occurs, in which unevaporated liquid refrigerant returns to the compressor, it causes failure of the compressor. Therefore, when the vapor compression refrigerator is constructed, the refrigerant must be completely evaporated in the evaporator portion. For this reason, a research was conducted to install a heat exchanger for refrigerant overheating between the evaporator and the compressor, and to use the heat of the engine cooling water to completely evaporate the refrigerant sent from the evaporator to the compressor. Has been done.

As a heat exchanger for overheating the refrigerant as described above, Japanese Patent Application No. 5-22880 or Japanese Patent Application Laid-Open No. 5-1644.
Japanese Patent Publication No. 83 discloses a heat exchanger called a so-called double tube heat exchanger. 3 to 5 show the above-mentioned actual application 5-2.
2 shows a double tube heat exchanger as disclosed in 2880. This double-pipe heat exchanger has a base end portion of a refrigerant inlet pipe 2 at one end (right end in FIG. 3) opening of an inner pipe 1 having a circular cross section and a refrigerant outlet at another end (left end in FIG. 3) opening. The base ends of the pipes 3 are connected by fitting them inside. Around the inner pipe 1, an outer pipe 4 having an inner diameter sufficiently larger than the outer diameter of the inner pipe 1 and a length dimension smaller than the length dimension of the inner pipe 1 is provided. The inner pipe 1 is arranged concentrically with the both ends of the inner pipe 1 so as to project from both ends of the outer pipe 4. Therefore, a cylindrical water passage space 5 is provided between the inner peripheral surface of the outer pipe 4 and the outer peripheral surface of the inner pipe 1. Then, a pair of closing plates 6 and 6 each formed in a ring shape.
With this, both ends of the water passage space 5 are closed and the outer pipe 4 is supported.

As shown in FIG. 5 or FIG. 2 showing the present invention, the closing plate 6 has a U-shaped cross section, and the inner peripheral side cylindrical portion 7 is at the end of the inner pipe 1 and the outer peripheral side cylindrical portion. The part 8 is externally fitted to the end of the outer pipe 4, and the fitting parts are brazed to close the openings at both ends of the water passage space 5. As such a blocking plate, a blocking plate formed in a flat plate shape without forming the cylindrical portions 7 and 8 as described above is adopted, and the outer peripheral edge of such a flat plate blocking plate is used as an outer tube. 4 may be welded and the inner peripheral edge may be brazed to the outer peripheral surface of the end portion of the inner pipe 1 to close the openings at both ends of the water passage space 5.

An outlet side circular hole 9 is formed in one end portion (the right end portion in FIG. 3) of the outer pipe 4, and the base end portion of the outlet water pipe 10 is inserted into the outlet side circular hole 9. . On the other hand, an inlet side circular hole 11 is formed in the other end portion (the left end portion in FIG. 3) of the outer pipe 4, and the proximal end portion of the inlet water pipe 12 is inserted into the inlet side circular hole 11. There is. Then, by brazing the respective constituent members 1, 2, 3, 4, 6, 10, 12 made of aluminum material (aluminum and aluminum alloy) liquid-tightly, a double-tube heat exchanger is obtained. Complete.

When this double tube heat exchanger is used, the refrigerant flows from the refrigerant inlet tube 2 to the refrigerant outlet tube 3 and flows from the right side to the left side in FIG. Engine cooling water flows from the left to the right in FIG. 3 into the water passage space 5 toward the outlet water pipe 10. As a result, the refrigerant and the cooling water exchange heat via the inner pipe 1, and the refrigerant flowing in the inner pipe 1 is heated. Therefore, even if the liquid refrigerant which has not been evaporated is mixed in the refrigerant sent from the refrigerant inlet pipe 2 into the inner pipe 1, the liquid refrigerant is completely evaporated while flowing through the inner pipe 1, and the superheated steam is generated. Then, it is sent out from the refrigerant outlet pipe 3 toward the compressor.

In the double-tube heat exchanger disclosed in Japanese Patent Laid-Open No. 5-164483, the inner pipe 1 and the outer pipe 4 are integrally formed, and fins are formed on the outer peripheral surface of the inner pipe 1. It is provided integrally. Other basic configurations and operations are
This is similar to the double-tube heat exchanger described above.

[0009]

In the conventional double pipe heat exchanger as described above, when the cooling water is fed from the inlet water pipe 12 into the water passage space 5, the inlet water pipe is The cooling water collides with one end side portion (the left end side portion in FIG. 3) of the inner pipe 1 facing the base end opening (entrance side circular hole 11) of 12. For this reason, the one end side portion is more likely to be corroded than the other portions due to the stress based on the water pressure of the cooling water. When the inner pipe 1 corrodes in the plate thickness direction, that is, when so-called pitting corrosion occurs, a through hole is formed in the inner pipe 1, and the refrigerant flowing inside the inner pipe 1 leaks out of the inner pipe 1. , The heat exchanger does not work properly.

The heat exchanger disclosed in Japanese Patent Application No. 5-22880 uses a clad material in which a sacrificial material is laminated on the surface of a core material for each constituent member such as the inner tube 1 which comes into contact with cooling water. Since it is configured, the above-mentioned pitting corrosion is unlikely to occur. However, even in the structure having the sacrificial material as described above, pitting may occur on the one end side portion due to the stress based on the hydraulic pressure of the cooling water with long-term use. The double-tube heat exchanger of the present invention has been considered in view of the above circumstances.

[0011]

The double-tube heat exchanger of the present invention, like the above-mentioned conventional double-tube heat exchanger, is an inner tube having a circular cross section made of an aluminum material. And a refrigerant inlet pipe and a refrigerant outlet pipe connected by fitting the respective base end portions into both end openings of the inner pipe, and having an inner diameter sufficiently larger than the outer diameter of the inner pipe, An outer pipe arranged concentrically with the inner pipe around the inner pipe, and a water passage space provided between the inner peripheral surface of the outer pipe and the outer peripheral surface of the inner pipe, each formed in an annular shape. A pair of closing plates for closing the openings at both ends of the water passage space, an outlet side circular hole formed at one end of the outer pipe, and an outlet water pipe having a base end portion inserted into the outlet side circular hole And an inlet side circular hole formed at the other end of the outer pipe, and an inlet water pipe having the base end portion inserted into the inlet side circular hole.

Particularly, in the double-tube heat exchanger of the present invention, the cover plate member is fitted and fixed to the outer peripheral surface of the one end side portion of the inner pipe facing the inlet side circular hole. The part has a double structure.

[0013]

With the double-tube heat exchanger of the present invention configured as described above, the operation itself when heat-exchanges the refrigerant flowing through the inner pipe and the cooling water flowing through the water passage space is The same as the conventional double-tube heat exchanger described above. Particularly, in the double-tube heat exchanger of the present invention, the cover plate is fitted and fixed on the outer peripheral surface on one end side of the inner tube where the cooling water fed through the inlet side circular hole collides. Due to this, this part has a double structure. For this reason, the one end side portion of the inner pipe with which the cooling water sent through the inlet side circular hole collides becomes thick, and even if this portion corrodes, a through hole is less likely to occur.

[0014]

FIG. 1 shows a first embodiment of the present invention.
In the present invention, the cooling water sent from the inlet water pipe 12 to the water passage space 5 penetrates the end portion of the inner pipe 1 facing the base end opening (entrance side circular hole 11) of the inlet water pipe 12 by corrosion. The structure is characterized by preventing the formation of holes, and the other structures are the same as those of the double-tube heat exchanger of Japanese Patent Application No. 5-22880 shown in FIGS. . Therefore, the same parts are designated by the same reference numerals, and the duplicated description will be omitted. Hereinafter, the characteristic part of the present invention will be mainly described.

An inlet side circular hole 11 is provided at one end side (the left end side in FIG. 1) of the outer pipe 4, and an inlet water pipe 12 is provided in the inlet side circular hole 11.
Is provided. Further, a closing plate 6a is provided at one end of the outer tube 4. The closing plate 6a has a U-shaped cross-section like the closing plate 6 described above, and includes an inner peripheral side cylindrical portion 7a externally fitted to one end portion (the left end portion in FIG. 1) of the inner pipe 1, and an outer pipe. 4 and an outer peripheral side cylindrical portion 8 fitted on one end portion of the outer peripheral portion 4. Then, one end portion of the outer tube 4 is tightly closed by externally fitting each of these cylindrical portions 7a and 8 onto each of the tubes 1 and 4, and then brazing. The closing plate provided at the other end of the outer tube 4 may have a structure like the closing plate 6a (6) having a U-shaped cross section, or may be the above-mentioned flat plate-like closing plate. Is also good.

Particularly, in this embodiment, the closing plate 6 is used.
The inner cylindrical portion 7a of a extends to a position facing the inlet water pipe 12. Therefore, when the closing plate 6a is assembled to the outer pipe 4, the inner peripheral side cylindrical portion 7a covers a portion of the inner cylinder 1 facing the base end opening of the inlet water pipe 12 on one end side. The extended inner peripheral side cylindrical portion 7a forms a cover plate material.

Since the double pipe heat exchanger of the present invention is constructed as described above, the thickness of the entire one end side portion of the inner pipe 1 facing the inlet water pipe 12 becomes large. As a result, it is difficult to form a through hole due to pitting corrosion in the above portion. Further, the closing plate 6a and the inner pipe 1 are made of a clad material in which a sacrificial material is laminated on the surface of a core material. Therefore, even when the stress based on the hydraulic pressure of the cooling water sent from the cooling water pipe 12 into the water passage space 5 continues to act on the portion where the covering plate material is fitted, first, the inner peripheral side which is the covering plate material. The sacrificial material forming the cylindrical portion 7a is corroded, and the corrosion hardly reaches the inner pipe 1. In this way, by increasing the thickness of the one end side portion and the presence of the sacrificial material, these effects are combined, and the double-tube heat exchanger of the present invention operates stably over a long period of time. .

Next, FIG. 2 shows a second embodiment of the present invention. In the present embodiment, the cylindrical member 13 is provided outside the one end side portion (the left end side portion in FIG. 2) of the inner pipe 1 facing the base end opening (the inlet side circular hole 11) of the inlet water pipe 12. It is fitted. As a result, this portion has a double structure. The cylindrical member 13 forms a cover plate material. Further, in the present embodiment, the convex portions 14 are formed by bulging the portions of the inner pipe 1 and the cylindrical member 13 facing the inlet water pipe 12 over the entire circumference. . The formation of the convex portion 14 is
After the cylindrical member 13 is externally piped to the inner pipe 1, an elastic material such as rubber is inserted into the inner pipe 1 and the elastic material is axially compressed to increase its outer diameter. It is carried out by a conventionally known means such as applying pressure from the inside.

Since the present embodiment is constructed as described above, the strength of the one end side portion of the inner pipe 1 facing the inlet water pipe 12 is increased, and the presence of the convex portion 14 causes the inlet water pipe 12 to be present. The flow of water sent from is diffused, and the stress applied to the one end side portion by the water flow is reduced. As a result, corrosion is unlikely to occur in that portion. However, if a gap is formed between the inner tube 1 and the cylindrical member 13,
The presence of this gap causes crevice corrosion. Therefore, the inner tube 1 and the cylindrical member 13 are fitted and then brazed so that the above-mentioned gap is not generated. For the brazing, for example, a brazing material layer is provided on the outer peripheral surface of the inner tube 1 or the inner peripheral surface of the cylindrical member so that the above parts are brazed to each other during heating brazing of the heat exchanger. Can be done easily.

It should be noted that by forming the above-mentioned convex portion on one end side portion of the inner pipe 1 facing the inlet water pipe 12 without externally fitting the cylindrical member 13 on the inner pipe 1, the water It is also conceivable to diffuse the flow to prevent corrosion of the relevant part.
However, in the case of the structure in which only the convex portion is formed on the inner pipe 1 as described above, while the stress due to the water flow can be relieved, the formation of the through hole is likely due to the possibility of increased corrosion due to the increase of internal stress in the convex portion forming portion. The prevention effect is weak. In addition, a plate material is provided (attached) only to a portion of the inner pipe 1 facing the base end opening of the inlet water pipe 12 and the water sent from the inlet water pipe 12 directly contacts the inner pipe 1. It is also possible to do. However, in this case, when assembling the heat exchanger, it is difficult and unrealistic to correctly make the portion of the inner pipe 1 where the plate member is provided face the proximal end opening of the inlet water pipe 12.

In the double-pipe heat exchanger of the present invention, the portion of the inner pipe 1 facing the base end opening of the inlet water pipe 12 is
It is characterized in that the cover plate is externally fitted so that the part has a double structure. Therefore, although not shown in the drawings, unlike the above-mentioned first, second, and respective embodiments, for example, a through-hole formation preventing effect can be obtained even if a structure in which a cylindrical member is simply fitted and fixed to one end portion of the inner pipe is used. Will improve.

Further, each of the constituent members constituting the above-mentioned double-tube heat exchanger has a brazing material on the surface like the double-tube heat exchanger disclosed in the above-mentioned Japanese Patent Application No. 5-22880. This is completed by temporarily stacking the constituent members into a laminated clad material and then brazing in a heating furnace. Further, on the surface of each of the above-mentioned constituent members, the surface facing the water passage space 5 through which the cooling water flows is covered with a sacrificial material. That is, the outer tube 4 is
A sacrificial material is formed on the inner peripheral surface of the core material, and a brazing material is formed on the outer peripheral surface of the core material. Also, the outlet water pipe 10
(FIG. 3) and the inlet water pipe 12 are made of a clad material in which a sacrificial material is laminated on the inner peripheral surface and the outer peripheral surface of the core material. The pair of blocking plates 6a are made of a clad material in which a sacrificial material is laminated on the inner surface facing the water passage space 5 and a brazing material is laminated on the outer surface on the opposite side. Therefore, pitting corrosion is unlikely to occur in the inner pipe 1, the outer pipe 4, and the closing plate 6a, and there is little risk that the members 1, 4, 6a will be pitted due to corrosion. Furthermore, the inner peripheral surfaces of the outlet water pipe 10 and the inlet water pipe 12 are also
Since the water pipes 10 and 12 are covered with the sacrificial material, it is less likely that pitting corrosion will occur from the inner peripheral surface side. Furthermore, since the ends of the hoses for flowing the cooling water are externally fitted to the tips of the outlet water pipe 10 and the inlet water pipe 12, the cooling water also touches the outer peripheral surfaces of the tips of the water pipes 10 and 12. Since the outer peripheral surfaces of the water pipes 10 and 12 are also covered with the sacrificial material, the respective water pipes 10 and 12
However, there is little possibility that pitting corrosion will occur from the outer peripheral surface side. In addition to such a configuration, since the one end side portion of the inner pipe 1 is also less likely to cause pitting corrosion, the double-tube heat exchanger of the present invention does not cause pitting corrosion. It is suppressed and stable operation is obtained over a long period of time. Moreover, in the case of the structure shown in the second embodiment, the presence of the convex portion 14 makes it difficult for the inner pipe 1 to be displaced from other members after the temporary assembly, so that a defective product is generated due to the displacement. Can be prevented.

In each of the first and second embodiments shown in FIGS. 1 and 2, the length of the outer tube 4 in the axial direction (left-right direction in FIGS. 1 and 2) is set to the inner tube. 1 shows a structure in which the length of the inner pipe 1 is made smaller than that of the inner pipe 1 and both ends of the inner pipe 1 are projected from the openings of both ends of the outer pipe 4, the double pipe heat exchanger of the present invention. Is not limited to such a structure, and for example, the inner tube 1 and the outer tube 4 may have the same axial length.

[0024]

EFFECTS OF THE INVENTION Since the double pipe heat exchanger of the present invention is constructed and operates as described above, the portion of the inner pipe facing the inlet water pipe, which was apt to generate pitting corrosion in the past, generated pitting corrosion. It becomes difficult to do, and excellent durability can be secured. As a result, the double-tube heat exchanger can be stably operated over a long period of time.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part showing a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part, showing a second embodiment of the present invention.

FIG. 3 is a front view showing the overall structure of a double-tube heat exchanger.

FIG. 4 is a view seen from the left side of FIG.

5 is a view corresponding to a cross section taken along the line AA of FIG.

[Explanation of symbols]

 1 Inner Pipe 2 Refrigerant Inlet Pipe 3 Refrigerant Outlet Pipe 4 Outer Pipe 5 Water Passing Space 6, 6a Blocking Plate 7, 7a Inner Circular Cylinder 8 Outer Circular Cylinder 9 Outlet Circular Hole 10 Outlet Water Pipe 11 Inlet Circular 12 Inlet water pipe 13 Cylindrical member 14 Convex part

Claims (1)

[Claims] 1. An inner pipe having a circular cross-section, each made of an aluminum material, and a refrigerant inlet pipe and a refrigerant outlet pipe connected by fitting respective base end portions into both end opening portions of the inner pipe. And an outer tube having an inner diameter sufficiently larger than the outer diameter of the inner tube and arranged concentrically with the inner tube around the inner tube, an inner peripheral surface of the outer tube and an outer peripheral surface of the inner tube. And a pair of closing plates, each of which is formed in a ring shape and closes both end openings of the water passing space, and an outlet side provided at one end of the outer pipe. A circular hole, an outlet water pipe whose base end is inserted in the outlet side circular hole, an inlet side circular hole formed in the other end of the outer pipe, and a base end portion in the inlet side circular hole. In a double-tube heat exchanger having an inserted inlet water pipe, a cover plate material is fitted to the outer peripheral surface of one end side portion of the inner pipe facing the inlet side circular hole. A double-tube heat exchanger characterized by having a double structure in that part by fixing together.